The Growth Hormone Releasing Hormone Analogue, Tesamorelin, Decreases Muscle Fat and Increases Muscle Area in Adults with HIV.

BACKGROUND: Tesamorelin, a growth hormone-releasing hormone analogue, decreases visceral adipose tissue in people living with HIV, however, the effects on skeletal muscle fat and area are unknown. OBJECTIVES: The goals of this exploratory secondary analysis were to determine the effects of tesamorelin on muscle quality (density) and quantity (area). DESIGN: Secondary, exploratory analysis of two previously completed randomized (2:1), clinical trials. SETTING: U.S. and Canadian sites. PARTICIPANTS: People living with HIV and with abdominal obesity. Tesamorelin participants were restricted to responders (visceral adipose tissue decrease ≥8%). INTERVENTION: Tesamorelin or placebo. MEASUREMENTS: Computed tomography scans (at L4-L5) were used to quantify total and lean density (Hounsfield Units, HU) and area (centimeters2) of four trunk muscle groups using a semi-automatic segmentation image analysis program. Differences between muscle area and density before and after 26 weeks of tesamorelin or placebo treatment were compared and linear regression models were adjusted for baseline and treatment arm. RESULTS: Tesamorelin responders (n=193) and placebo (n=148) participants with available images were similar at baseline; most were Caucasian (83%) and male (87%). In models adjusted for baseline differences and treatment arm, tesamorelin was associated with significantly greater increases in density of four truncal muscle groups (coefficient 1.56-4.86 Hounsfield units; all p<0.005), and the lean anterolateral/abdominal and rectus muscles (1.39 and 1.78 Hounsfield units; both p<0.005) compared to placebo. Significant increases were also seen in total area of the rectus and psoas muscles (0.44 and 0.46 centimeters2; p<0.005), and in the lean muscle area of all four truncal muscle groups (0.64-1.08 centimeters2; p<0.005). CONCLUSIONS: Among those with clinically significant decrease in visceral adipose tissue on treatment, tesamorelin was effective in increasing skeletal muscle area and density. Long term effectiveness of tesamorelin among people with and without HIV, and the impact of these changes in daily life should be further studied.

Activity of (-)-2'-deoxy-3'-oxacytidine (BCH-4556) against human tumor colony-forming units.

BACKGROUND: BCH-4556 ((-)-2'-deoxy-3'-oxacytidine) is an L-nucleoside analogue shown to have broad preclinical anti-cancer activity, particularly against solid neoplasms such as prostate, renal, and hepatoma in vitro and in vivo, in contrast to cytosine arabinoside (ara-C) which is preferentially active against leukemia. MATERIALS AND METHODS: The antitumor activity of BCH-4556 was evaluated using human tumor colony-forming unit (HTCFU) assay, in which fresh tumor specimens were taken directly from patients with and without prior chemotherapy. RESULTS: Overall, in vitro responses (50% or less survival compared to untreated controls) were observed in 11% (two of 18), 29% (five of 17) and 50% (nine of 18) of specimens treated for one hour with BCH-4556 at 1, 10 and 100 micrograms/ml, respectively; and 16% (nine of 55), 32% (24 of 74), 48% (35 of 73) and 65% (11 of 17) of specimens treated continuously with BCH-4556 at 0.1, 1, 10 and 100 micrograms/ml, respectively. With the one-hour schedule, a significant difference in response rates was noted between 100 micrograms/ml and 1 microgram/ml (P = 0.02). With the continuous schedule, significant differences in response rates were observed between 1 microgram/ml and 0.1 microgram/ml (P = 0.02), between 10 micrograms/ml and 0.1 microgram/ml (P = 0.0001), as well as between 10 micrograms/ml and 1 microgram/ml (P = 0.01). A trend suggesting the superiority of continuous exposure was observed in paired specimens (n = 18) at comparable drug concentrations. Activity was noted against ovarian (nine of 16 = 56%), renal (three of four = 75%), and melanoma (two of two = 100%) HTCFU at 10 micrograms/ml using the continuous schedule. Comparisons between BCH-4556 and paclitaxel were made in 32 specimens at 10 micrograms/ml using the continuous exposure. Twenty-three specimens showed similar responses with both drugs; seven showed better responses with BCH-4556; and two showed better responses with paclitaxel (P = 0.18). CONCLUSIONS: Promising activity was observed with BCH-4556 against ovarian, renal, and melanoma HTCFU. There appeared to be a positive relationship between BCH-4556 concentration and response using both one-hour and continuous exposures. Continuous exposure to BCH-4556 provided high response rates especially at concentrations above 10 micrograms/ml. For both one-hour and continuous exposures, BCH-4556 had similar, and at times, greater potency than paclitaxel against the same tumor specimens in the present study.

Reassessment of 14CO2 compartmentation and of [14C]formate oxidation in rat liver.

Our previous report (Marsolais, C., Huot, S., David, F., Garneau, M., and Brunengraber, H. (1987) J. Biol. Chem. 262, 2604-2607) had concluded that a fraction of [14C]formate oxidation in liver occurs in the mitochondrion. This conclusion was based on the labeling patterns of urea and acetoacetate labeled via 14CO2 generated from [14C]formate and other [14C]substrates. We reassessed our interpretation in experiments conducted in (i) perifused mitochondria and (ii) isolated livers perfused with buffer containing [14C]formate, [14C]gluconolactone, 14CO2, or NaH13CO3, in the absence and presence of acetazolamide, an inhibitor of carbonic anhydrase. Our data show that the cytosolic pools of bicarbonate and CO2 are not in isotopic equilibrium when 14CO2 is generated in the cytosol or is supplied as NaH14CO3. We retract our earlier suggestion of a mitochondrial site of [14C]formate oxidation.

Compartmentation of 14CO2 in the perfused rat liver.

The specific activity of the mitochondrial CO2 + bicarbonate system has been measured in perfused livers using the specific activities of urea and acetoacetate derived from 2-ketoisocaproate catabolism. Label was supplied either as NaH14CO3, 2-keto[1-14C]isocaproate, [1-14C]pyruvate, [1-14C]glutamine, or [14C]formate. With labeled bicarbonate, pyruvate, or 2-ketoisocaproate, the specific activities of effluent bicarbonate, urea, and acetoacetate were equal (acetoacetate was labeled only on C-1). In the presence of [14C]formate, the specific activity of acetoacetate was double that of urea. Acetazolamide (0.2 mM), an inhibitor of carbonic anhydrase, decreased the specific activities of urea and acetoacetate labeled from NaH14CO3 and increased the specific activities of urea and acetoacetate labeled from the other tracers. We conclude that: acetoacetate derived from 2-ketoisocaproate is, like urea, an index of the specific activity of mitochondrial CO2 in liver, carbonic anhydrase activity equalizes the specific activities of the CO2 + bicarbonate system on both sides of the mitochondrial membrane, and a fraction of [14C] formate-derived 14CO2 appears to be generated in a mitochondrial compartment, in the close vicinity of methylcrotonyl-CoA carboxylase.